This invention relates to a method of creating a reference table helpful to high-speed computing, for example, in a fabrication process simulation of a semiconductor device.
In the field of the semiconductor device fabrication process simulation, an object is abstracted into a simulation model for the sake of simple computing. The simulation model is further divided into a plurality of elements, each of which is handled as a target of observation or prediction of the phenomenon occurring at the object.
Such a process simulation technique is disclosed in Japanese Unexamined Patent Publication (JP-A) No. 10-135145, which is incorporated herein by reference. In JP-A No. 10-135145, a simulation object is a two-dimensional object, and elements are triangle elements. In an ion-implantation simulation, the triangle element that an implanted ion reaches is computed.
Generally, all triangle elements are not searching targets in the ion-implantation simulation to prevent a large amount of computing. In spite of this, normal approach uses a plural-rectangular arrangement, for example, an orthogonal mesh arrangement. In advance of a process simulation, a reference data table is created, where rectangular pieces and triangle elements are registered in connection with each other. In the process simulation, a specific rectangular piece is at first selected in correspondence with a location the implanted-ion reaches, then only the triangle elements that are connected with the specific rectangular piece are handled as computing targets, with reference to the pre-created reference data table. Thus to use the reference data table can decrease the number of the triangle elements as the computing targets, and therefore, the reference data table is helpful to lower amount of computing the triangle element the implanted-ion reaches.
For the reference data table to be more efficient, each of rectangular pieces needs to be small in size. Otherwise, the number of the triangle elements that are connected with one rectangular piece becomes large, resulting in large amount of the computation to be required to search the triangle element that an implanted-ion reaches. However, if each rectangular piece is small in size, a large amount of computation is required in previously creation of the reference data table.
In light of the foregoing, there is a need to reduce an amount of computation required for creation of the reference data table even if rectangular piece is small in size.
This invention therefore provides a method of creating a reference data table which accompanies with a small amount of computation if rectangular piece is small in size.
According to one aspect of this invention, a method of creating a reference data table comprises following steps which are executed by a processor. In advance of the reference data table creation, a two-dimensional rectangular coordinates is configured to cover a two-dimensional object. In addition, the two-dimensional object is divided into a plurality of polygon elements. Each of the polygon elements has vertexes and edges connecting between two vertexes. Also, each of the polygon elements has, as a element number, a unique number added to the polygon element. Furthermore, a two-dimensional orthogonal mesh is produced on the two-dimensional rectangular coordinates. The two-dimensional orthogonal mesh comprises a plurality of rectangular pieces which are regularly arranged on the two-dimensional rectangular coordinates and each of which has, as a piece number, a unique number added to the rectangular piece.
The processor makes an initial data table having two column and a plurality of rows, each of rows at one column storing the piece numbers of the rectangular pieces, respectively. Then the processor carries out a predetermined registration process for each of the polygon element as a target polygon element so that, when the predetermined registration process is repeatedly carried out for all of the polygon element, the reference data table is obtained.
In detail, the predetermined registration process generally comprises three steps. Firstly, the processor searches, as first searched rectangular pieces, the rectangular pieces that include the vertexes of the target polygon element, and then registers the element number of the target polygon element for the rows corresponding to the first searched rectangular pieces. Secondly, the processor searches, as second searched rectangular pieces, the rectangular pieces that are traversed by the edges of the target polygon element, and then registers the element number of the target polygon element for the rows corresponding to the second searched rectangular pieces. Thirdly, the processor registers the element number of the target polygon element for the rows corresponding to the rectangular pieces that exist within the target polygon element. Thus the element number of the target polygon element is registered with all of the rectangular pieces overlapping the target polygon element.
As well known to the inventor, there are similar problems in a simulation using a three-dimensional object. That is, there is a need to reduce an amount of computation required for creation of the reference data table if rectangular block has small volume.
In relation, the above-mentioned method of creating the reference data table can be modified or extended to handle the three-dimensional object. In the simulation using the three-dimensional object, rectangular blocks and polyhedron elements are used in spite of the foregoing rectangular pieces and polygon elements. Also, a three-dimensional orthogonal coordinates is defined in spite of the two-dimensional orthogonal coordinates. It is noted here that, as for the second step of the foregoing predetermined registration process, the extended method uses faces of the target polyhedron in spite of the edges of the target polygon.